If you're evaluating a SEM agency, you're likely staring down a familiar problem: your organic traffic is solid, but you need revenue now. Paid search delivers results in days, not months — but only when it's managed well. The difference between a strong sem agency and a mediocre one isn't effort. It's strategy, accountability, and the infrastructure they build around your campaigns.

This guide breaks down exactly what a search engine marketing agency does, how to evaluate one, and what to watch out for before you sign anything.

What Does a SEM Agency Do?

A SEM agency manages paid search advertising across platforms like Google Ads and Microsoft (Bing) Ads. Their core job is to capture high-intent demand — people who are actively searching for what you sell — and convert that traffic into revenue.

That scope covers a lot of ground. Depending on the engagement, a paid search agency will:

• Conduct keyword research to identify terms that indicate purchase intent
• Build and structure campaigns (search, shopping, Performance Max, display)
• Write and test ad copy across multiple variations
• Set and continuously optimize bids using manual or automated strategies
• Build or audit landing pages to improve conversion rates
• Set up conversion tracking and attribution so you know what's actually working
• Report on performance with clear metrics tied to business outcomes

In 2026, the best agencies layer AI-driven bidding and dynamic asset generation on top of these fundamentals — but the fundamentals still have to be right. Automation without a sound account structure doesn't produce results; it just burns budget faster.

What to Look for in a SEM Agency

Not all paid search agencies are built the same. Here's what separates the performance-focused ones from those that generate reports without moving revenue.

Account ownership. You should own your Google Ads account — not the agency. If they want to run campaigns inside their own manager account with restricted access, that's a serious red flag. You need full ownership so the work stays with you if the relationship ends.

Conversion tracking done right. Sloppy attribution is one of the most common issues in paid search engagements. Look for agencies that implement server-side tracking or enhanced conversions, not just standard Google Tag Manager setups. If their measurement doesn't hold up under scrutiny, you can't trust their reporting.

Transparent communication on bidding strategy. Smart bidding (tCPA, tROAS, Maximize Conversions) can work well, but only with sufficient conversion data and the right targets. An agency should be able to explain clearly why they're using a specific bid strategy for your account, not just default to it because it's the path of least resistance.

Case studies with real numbers. Ask for documented client results. Not logos. Actual performance data — ROAS improvement, cost-per-acquisition reduction, revenue growth — from accounts similar to yours in size, industry, or model. Agencies that can't produce verifiable examples haven't earned the benefit of the doubt.

Landing page involvement. A SEM agency that only manages bids and ignores what happens after the click is leaving money on the table. The best agencies treat the landing page as part of the campaign, not someone else's problem.

For more on what to look for when hiring a paid advertising partner, see our guide to PPC management for ecommerce.

SEM Agency Pricing: What to Expect

SEM pricing varies significantly based on agency size, ad spend volume, and service scope. The three most common structures you'll encounter:

Percentage of ad spend. The agency charges 10–20% of your monthly ad budget. This model aligns incentives around scale — as your campaigns grow, so does the fee — but it can create misaligned incentives if the agency's income rises by increasing spend rather than improving efficiency.

Monthly retainer. A flat monthly fee, typically ranging from $1,500 to $10,000+ depending on scope. This model works well for companies with stable budgets and clear deliverables. Retainers often come with a one-time setup fee of $500–$3,500 covering account audits, restructuring, and tracking implementation.

Hybrid model. A base retainer covers core management, with performance bonuses tied to hitting specific targets (ROAS, CPA, revenue). This is increasingly common in 2026 because it creates shared accountability. You pay for baseline effort, and the agency earns more when results exceed thresholds.

Most reputable agencies require a minimum engagement of three to six months. Paid search campaigns need time to accumulate data, test variables, and optimize — asking for meaningful results in 30 days is unrealistic for most accounts.

Questions to Ask Before You Hire

Before signing with any search engine marketing agency, run through these questions in your evaluation calls:

• Who owns the Google Ads account, and what happens to it if we end the engagement?
• What conversion tracking setup do you use, and how do you handle attribution across channels?
• Can you share two or three case studies with actual performance data from accounts similar to ours?
• What's your process for the first 30, 60, and 90 days?
• How do you handle landing pages — do you build them, optimize them, or hand off recommendations?
• What does your reporting look like, and how often will we meet to review results?
• How do you approach bid strategy decisions, and what triggers a change?
• What's your policy on ad spend minimums?

Any agency that hedges heavily on account ownership, attribution, or case studies is worth passing on. The best partners are direct and specific.

SEM vs. SEO: When You Need Both

SEM and SEO serve different parts of the demand curve, and they work better together than in isolation.

SEO builds authority and captures intent at scale over time. A well-optimized site ranking for high-volume informational and commercial terms generates compounding returns — but those rankings take months to years to build. SEM, by contrast, is available immediately. You can be at the top of search results for high-intent terms tomorrow.

The strongest search marketing programs run both channels in parallel. SEO supports awareness and middle-of-funnel content. SEM covers bottom-of-funnel terms where purchase intent is explicit. Together, they create coverage across the entire search journey — and the data from paid search often informs which organic content is worth building.

For a deeper look at how these channels complement each other, see our breakdown of building a balanced SEO and SEM strategy.

How EmberTribe Approaches Paid Search

EmberTribe works primarily with DTC brands and growth-stage companies that need paid search to pull real revenue weight — not just generate impressions. Our approach is built around three principles.

First, clean infrastructure. Before we touch bids, we audit account structure, conversion tracking, and attribution. Garbage in, garbage out. If the measurement isn't right, every optimization decision downstream is built on sand.

Second, cross-channel integration. We don't treat Google Ads as an island. Our paid search work connects to creative testing, landing page strategy, and email and SMS flows — because the customer path rarely starts and ends in one place. If you're looking at how this fits into a broader growth strategy, our post on choosing the right marketing agency for your business covers how to evaluate that full-picture thinking.

Third, accountability to revenue. ROAS and CPA are proxies. We work back from the number that matters — revenue — and build campaigns with that target as the anchor.

If your paid search isn't performing to its potential, or you're evaluating SEM agencies for the first time, we're happy to take a look at your current setup and tell you exactly what we see.

Get a free paid search audit from EmberTribe and walk away with a clear picture of what's working, what isn't, and what a focused sem agency engagement could deliver for your business.